1. Field of the Invention
Aspects of the present invention relate to an apparatus and method to estimate a playback time of audio data and, more particularly, to an audio playback time estimating apparatus and method that can effectively estimate an average bit rate of audio data compressed in a variable bit rate manner.
2. Related Art
Currently, there are a variety of audio compression techniques, including WMA (Windows Media Audio), AAC (Advanced Audio Coding), OGG (Ogg Vorbis), MP3 (MPEG Audio Layer-3), and others. MP3 is a high audio quality audio compression technique specified by the MPEG-1 specification that compresses audio data by frames having independent bit rates. When compressing audio data in MP3 format, the same compression rate, hereinafter referred to as a constant bit rate (CBR), or different compression rates, hereinafter referred to as a variable bit rate (VBR), may be applied to various frames of the audio data. The MP3 audio format is widely used over the Internet because the MP3 audio format compresses audio data 50 times relative to CD audio data, while maintaining CD-quality audio.
A digital audio player, such as an MP3 player, supplies a user with information concerning audio data when playing back the audio data, e.g., an average bit rate, a playback time, and the like. Conventionally, all frames constituting the audio data are scanned to obtain a bit rate of each frame, a play back time, the average bit rate, and the like. However, the scanning time may be undesirably extended if oversized audio data is scanned or a low-performance player is used for scanning.
To solve this problem, a technology has been proposed in which bit rates and playback time are obtained for only K frames occurring at the beginning of the audio data, and average values thereof are estimated as the average bit rate and playback time of the audio data. According to the proposed technology, while estimation of a playback time of audio data compressed at a constant bit rate is relatively accurate, estimation of an accurate playback time of audio data compressed at a variable bit rate cannot be ensured.